Hi!
This month we have a rather exotic rectifier. Meet the G2504.
The G2504 is a directly heated full wave rectifier tube. It is equivalent to the RGN2504.
The tube has a European 4-Pin B4 base. The pinout is shown on the left. Unfortunately not much technical data can be found about this rectifier. The information I found states plate to plate voltage 500 V RMS and an output current of 180mA. I couldn't find anything about operation with capacitor input or choke input filters, peak inverse voltage or voltage drop. Since I do not have any G2504 tubes myself, Josef from Vienna was so kind to lend me some to take photos. He sent two different version of G2504. Both made by Valvo. One with mesh plates and the other with more common solid plates. Lets have a look at them starting with the mesh plate version.
Some close ups showing the mesh structure of the plates:
Some more views:
When the filament is lit up it is nicely visible through the mesh plate:
Next we have the G2504 with solid plates:
Close ups:
Some more views:
Obviously the filaments are not as visible as on the mesh plate when lit up. Just the tips at the top show the glow:
Thanks to Josef for lending me these tubes!
Best regards
Thomas
That's an interesting change. How did you get invested in american tubes so heavily but (seemingly) left out the German/European classics? Did you live next to a US military base and had access to their dead stock?
ReplyDeleteHi! There are some european tubes in this series. When I started to get into tubes american types were more easily accessible to build up a stock
ReplyDeleteWhy is it that tubes were made with mesh plates and not with solid plates? is there any advantage to it?
ReplyDeleteDid you listen to these? I’m wondering what the sonic differences are between the two.
ReplyDeleteThese are rectifiers. A rectifier does not have a sonic characteristic which is the same in different amps. If a rectifier has an impact on the sound which IMHO it only has in poorly designed circuits, it cannot be the same over the many different varieties of power supply circuits and amplifier circuits
DeleteWell, I guess Lampi dacs are poorly designed. I've had lots of rectis and have listened to plenty of them whose individual effect have changed the tone, too often that I don't like, and no other change could overcome it.
DeleteIt is mostly the effect of the different parameters of the rectifier on the rest of the circuit which changes the sound. And I stay firm with this if a circuit changes sound significantly with changing rectifiers it is a sign of a marginal design, be it intentionally or not. Nowadays people swap very different rectifiers in the same amp despite the rectifiers having very different properties. Normally a design should be optimised for a certain type and sound optimally with that type without any need to find the 'optimally sounding' rectifier. But that is just my opinion
Delete